This proposal is for an individual Physician Scientist Award to receive intensive training in basic biomedical research in the field of developmental neurobiology. Training will be carried out in Dr. Corey Goodman's laboratory at Stanford University. Phase I of the proposal includes both didactic study and intense laboratory experience. The applicant will be involved in courses, seminars, extensive literature reviews, and tutorials in advanced developmental biology, developmental neurobiology, molecular neurobiology, and eukaryotic gene expression. At the same time, the program will include extensive research training in monoclonal antibody technology, Drosophila embryology, biochemistry, and cDNA expression cloning technology. Phase II will be fully devoted to intensive research on the embryogenesis of neuronal specificity. The long term goal of this research program is to understand the molecular mechanism underlying cell recognition during the embryonic development of the central nervous system. An ideal model system for such molecular genetic studies is the Drosophila embryo. Previous studies provided evidence for the presence of molecular differences on the surfaces of axon fascicles during embryonic development. In order to isolate and characterize these surface molecules involved in cell recognition during neuronal development, monoclonal antibody and cDNA expression cloning technologies will be applied to the Drosophila embryo. The specific aims are: (i) to generate monoclonal antibodies that recognize surface molecules on specific subsets of embryonic neurons; and (ii) to screen these MAbs on a cDNA expression library in an attempt to isolate the genes which encode these molecules.